regulator: lochnagar: Add on_off_delay for VDDCORE

The VDDCORE regulator takes a good length of time to discharge down, so
add an on_off_delay to ensure DCVDD is removed before it is powered on
again.

Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20191001132017.1785-1-ckeepax@opensource.cirrus.com


Signed-off-by: Mark Brown <broonie@kernel.org>